Means for supporting fuel elements in a nuclear reactor

Abstract

5. A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members forming .[.at least one.]. longitudinally extending .[.opening.]. .Iadd.peripheral and inner fuel element openings .Iaddend.through .Iadd.each of .Iaddend.which .Iadd.openings .Iaddend. at least one nuclear fuel element extends, said connecting members forming wall means surrounding .[.said.]. .Iadd.each peripheral and inner fuel element .Iaddend.opening, a pair of rigid projections .Badd.longitudinally spaced from one another .Baddend.extending from a portion of said wall means into .[.said.]. .Iadd.each peripheral and inner .Iaddend.opening for rigidly engaging .[.said.]. .Iadd.each .Iaddend.fuel element, .Iadd.respectively, yet permit individual longitudinal slippage thereof, .Iaddend.and resilient means .Badd.formed integrally on and from said wall means and .Baddend.positioned in .[.said.]. .Iadd.each peripheral and inner .Iaddend.opening in opposed relationship with said projections and located to engage said fuel element to bias the latter into engagement with said rigid projections, .Iadd.respectively. .Iaddend.

We claim: .Badd..[..[.1. A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members forming .[.respective openings.]. .Iadd.peripheral and inner fuel element openings .Iaddend.through .[.which.]. .Iadd.each of which openings an .Iaddend.elongated .[.elements are.]. .Iadd.fuel elements is .Iaddend.adapted to extend, at least two rigid spaced projections extending into each of .[.at least some of.]. said .[.grid.]. .Iadd.peripheral and inner fuel element .Iaddend.openings from at least one of said members, and at least one resilient means extending into each of said .[.some.]. .Iadd.peripheral and inner .Iaddend.openings from at least another of said members and disposed generally opposite to said two rigid projections with its innermost protrusion being positioned in alignment with the region intermediate said spaced projections..]..]. .Badd..[..[.2. The combination of claim 1 wherein only one of said resilient means and said rigid means is located at the outer periphery of the grid structure..]..]..Baddend. .Badd..[..[.3. The combination of claim 1 wherein said projections of each of said .[.some.]. openings are longitudinally aligned, and wherein at least some of the innermost protrusions are longitudinally positioned midway between the generally opposed rigid projections..]..]. .Badd..[..[.4. A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members forming .[.at least one opening.]. .Iadd.peripheral and inner fuel element openings .Iaddend.through .Iadd.each of .Iaddend.which, .Iadd.respectively.Iaddend., at least one elongated .Iadd.fuel .Iaddend.element extends and .[.forming.]. .Iadd.forms .Iaddend.a segment of a flow channel .[.therebetween.]. .Iadd.between said fuel elements.Iaddend., rigid means engaging one side of .Iadd.all of .Iaddend.said elongated .[.element.]. .Iadd.elements, respectively.Iaddend., to laterally position .[.said.]. .Iadd.each .Iaddend.elongated element .Iadd.yet permit longitudinal slippage thereof.Iaddend., resilient means disposed on another side of .[.said.]. .Iadd.each .Iaddend.elongated element generally opposite to said one side and engaging .[.said.]. .Iadd.respectively each .Iaddend.elongated element to bias the latter into engagement with said rigid means, one of said rigid means and said resilient means extending from said connecting members into said .[.openening,.]. .Iadd.peripheral and inner openings .Iaddend.and the other of said rigid means and said resilient means being located in said flow channel..]..]. 5. A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members forming .[.at least one.]. longitudinally extending .[.opening.]. .Iadd.peripheral and inner fuel element openings .Iaddend.through .Iadd.each of .Iaddend.which .Iadd.openings .Iaddend.at least one nuclear fuel element extends, said connecting members forming wall means surrounding .[.said.]. .Iadd.each peripheral and inner fuel element .Iaddend.opening, a pair of rigid projections .Badd.longitudinally spaced from one another .Baddend.extending from a portion of said wall means into .[.said.]. .Iadd.each peripheral and inner .Iaddend.opening for rigidly engaging .[.said.]. .Iadd.each .Iaddend.fuel element, .Iadd.respectively, yet permit individual longitudinal slippage thereof.Iaddend., and resilient means .Badd.formed integrally on and from said wall means and .Baddend.positioned in .[.said.]. .Iadd.each peripheral and inner .Iaddend.opening in opposed relationship with said projections and located to engage said fuel element to bias the latter into engagement with said rigid projections, .Iadd.respectively.Iaddend.. 6. The combination of claim 5 wherein said pair of .Badd.longitudinally spaced .Baddend.rigid projections are longitudinally aligned on said wall means portion .[..[.and are longitudinally spaced from one another.]..]., and wherein said resilient means is positioned in alignment with the region intermediate said spaced projections. .Badd..[..[.7. The combination of claim 6 including another pair of longitudinally aligned spaced rigid projections extending from another wall means portion .Iadd.into each opening, respectively.Iaddend., said other wall means portion positioned laterally with respect to said first wall portion .Iadd.of each opening.Iaddend., and other resilient means positioned in .[.said.]. .Iadd.each .Iaddend.opening in opposed relationship with said other pair of projections and positioned to engage said fuel element to bias the latter into engagement with said other pair of projections..]..]. .Badd..[..[.8. The combination of claim 5 wherein said resilient means are formed integrally with said wall means..]..]..Baddend. 9. A grid structure for a nuclear reactor fuel assembly comprising a plurality of interlaced straps forming at least a pair of adjacent longitudinally extending openings with each of said openings having at least one elongated nuclear fuel element extending therethrough, at least a pair of longitudinally aligned spaced rigid projections extending from said straps into each of said openings for rigidly engaging the respective fuel element, resilient means extending from said straps into each of said openings in opposed relationship with said projections and positioned to engage said respective fuel element to bias the latter into engagement with the respective pair of rigid projections one of said straps forming a common wall between said adjacent openings, one of said pairs of spaced longitudinally aligned rigid projections being formed on said common wall and extending into one of said openings, and one of said resilient means being formed on said common wall and positioned intermediate and in longitudinal alignment with said .[..[.oen.]..]. .Badd.one .Baddend.pair of spaced projections, said one resilient means extending into the other of said openings. 10. A grid structure for a nuclear reactor fuel assembly comprising a plurality of interlaced straps forming at least a pair of adjacent longitudinally extending openings with each of said openings having at least one elongated nuclear fuel element extending therethrough, at least a pair of longitudinally aligned spaced rigid projections extending from said straps into each of said openings for rigidly engaging the respective fuel element, resilient means extending from said straps into each of said openings in opposed relationship with said projections and positioned to engage said respective fuel element to bias the latter into engagement with the respective pair of rigid projections, one of said straps forming a common wall between said adjacent openings, one of said pairs of spaced longitudinally aligned rigid projections being formed on said common wall and extending into one of said openings, and the other of said pairs of spaced longitudinally aligned rigid projections formed on said common wall and extending into the other of said openings, said one and said other pairs of rigid projections being longitudinally aligned with one another. 11. .[.The combination of claim 4 wherein.]. .Iadd.A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members forming at least one opening through which at least one elongated element extends and forming a segment of a flow channel therebetween, rigid means engaging one side of said elongated element to laterally position said elongated element, resilient means disposed on another side of said elongated element generally opposite to said one side and engaging said elongated element to bias the latter into engagement with said rigid means, one of said rigid means and said resilient means extending from said connecting members into said opening, and the other of said rigid means and said resilient means being located in said flow channel, .Iaddend.said connecting members .[.are.]. .Iadd.being .Iaddend.formed from straps extending laterally of said fuel elements, and including latching means in said straps for interfitting said straps with each other, and guide means disposed on said straps longitudinally opposite to said latching means for guiding the straps into an interfitted relationship. 12. The combination of claim 11 wherein said latching means are a plurality of slots extending partially through said straps in a longitudinal direction, and wherein said guide means comprise a plurality of dimples grouped in pairs, and the dimples in each pair are laterally aligned with each other and are spaced from each other approximately the thickness of said strap. 13. A grid structure for a nuclear reactor fuel assembly comprising a plurality of connecting members formed from interfitting cross-laced straps with .[.at least a portion.]. .Iadd.portions .Iaddend.of four of said straps forming .[.one.]. longitudinally extending .[.opening.]. .Iadd.peripheral and inner fuel element openings .Iaddend.through .Iadd.each of .Iaddend.which at least one nuclear fuel element extends, said connecting members forming wall means surrounding .[.said.]. .Iadd.each peripheral and inner fuel element .Iaddend.opening, a pair of spaced longitudinally aligned rigid projections extending from one of said strap portions into .[.said.]. .Iadd.each fuel element .Iaddend.opening for rigidly engaging said fuel element, first resilient means positioned in .[.said.]. .Iadd.each fuel element .Iaddend.opening in opposed relationship with said projections and positioned in alignment with the region intermediate said projections to engage said fuel element to bias the latter into engagement with said rigid projections another pair of longitudinally aligned spaced rigid projections extending from another of said strap portions .Iadd.into each fuel element opening.Iaddend., said other strap portion positioned adacent to said first strap portion, and second resilient means positioned in .[.said.]. .Iadd.each fuel element .Iaddend.opening in opposed relationship with said other pair of projections and positioned in alignment with the region intermediate the projections of said other pair to engage .[.said.]. .Iadd.each .Iaddend.fuel element .Iadd.respectively .Iaddend.to bias the latter into engagement with said other pair of projections, and said first and said second resilient means being formed respectively on .Badd.and from .Baddend.the remaining ones of said four strap portions. 14. A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, .[.at least one member.]. .Iadd.a plurality of longitudinally spaced grid members .Iaddend.extending laterally across said fuel arrangement, .[.and.]. .Iadd.said array including fuel elements that are permitted to individually expand and contract longitudinally relative to said grid members, said grid members positioning laterally in spaced relationship all of said fuel elements in said array that are permitted to individually expand and contract longitudinally relative to said grid members, each of said grid members .Iaddend.having respective openings .[.through which.]. .Iadd.therein all of .Iaddend.said .Iadd.longitudinally expandable .Iaddend.fuel elements .[.extend.]. .Iadd.in said array extending through respective openings in each grid member, each of .Iaddend.said grid .[.member.]. .Iadd.members .Iaddend..Badd.formed by a plurality of rigid walls and .Baddend.having both resilient means and substantially rigid means extending into each of .[.at least some of.]. said .Iadd.last mentioned openings for supporting all of .Iaddend.said .Iadd.longitudinally expandable .Iaddend.fuel elements against lateral displacement, .Badd.said rigid means in each opening including at least two longitudinally spaced contact regions integrally formed on a rigid wall, .Baddend.and said resilient means being .Badd.longitudinally spaced from and .Baddend.disposed generally opposite to said rigid means .Badd.and formed integrally on and from said walls.Baddend.. 15. .[.A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, at least one grid member forming respective openings through which said fuel elements extend, said grid member having resilient means and substantially rigid means resilient means and substantially extending into each of at least some of said openings for supporting said fuel elements against lateral displacement,.]. .Iadd.The fuel arrangement of claim 14 wherein .Iaddend.said rigid means .[.including.]. .Badd.forming said contact regions .Baddend..Iadd.includes .Iaddend.respective spaced projections extending into each of said .[.some.]. grid openings but being located opposite said resilient means, and said resilient means engaging said fuel elements at a location between said projections. .Badd..[..[.16. The combination of claim 15 wherein said spaced projections are disposed in groups of at least two longitudinally aligned projections..]..]..Baddend. 17. A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, elongated frame means juxtaposed and parallel to said fuel elements, .[.at least one.]. .Iadd.a plurality of longitudinally spaced .Iaddend.grid .[.member.]. .Iadd.members .Iaddend.being .[.secure.]. .Iadd.secured .Iaddend.to and extending laterally .[.across.]. .Iadd.from .Iaddend.said frame means .[.and.]., .Iadd.said array including fuel elements that are permitted to indivdually expand and contract longitudinally relative to said grid members, said grid members positioning laterally in spaced relationship all of said fuel elements that are permitted to individually expand and contract longitudinally and slip relative to said grid members, each of said grid members .Iaddend.forming respective .Iadd.aligned .Iaddend.openings through at least some of which .Iadd.aligned openings each of .Iaddend.said .Iadd.expanding .Iaddend.fuel elements .Iadd.respectively .Iaddend.extend, .Iadd.there being a group of longitudinally aligned fuel element openings for each expanding fuel element.Iaddend., said grid .[.member.]. .Iadd.members .Iaddend..Badd.being formed by a plurality of rigid walls and .Baddend.having resilient means and substantially rigid means extending into each of said fuel element openings for supporting .Iadd.all of .Iaddend.said .Iadd.expanding .Iaddend.fuel elements against lateral displacement, said resilient means including respective spring fingers .Badd.integrally formed on and from said walls and .Baddend.engaging said .Iadd.expanding .Iaddend.fuel elements, said rigid means including respective spaced projections extending .Badd.from said walls .Baddend.into each of said fuel element openings in groups of at least two axially aligned projections but being located generally opposite of said spring fingers, said spring fingers engaging said fuel elements at a location between said spaced projections, and four of said projections and two of said spring fingers extending into each fuel element opening. 18. .[.A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, at least one grid member extending laterally across said fuel arrangement and having at least one opening through which at least one of said fuel elements extend, substantially rigid means for rigidly engaging and laterally positioning said one fuel element, resilient means for biasing said one fuel element into engagement with said rigid means, said resilient means being disposed generally opposite to said rigid means, and.]. .Iadd.The fuel arrangement of claim 14 wherein .Iaddend.at least one of said rigid means and said resilient means .[.being.]. .Iadd.is .Iaddend.disposed on .Iadd.each of .Iaddend.said grid .[.member.]. .Iadd.members .Iaddend.and .[.extending.]. .Iadd.extend .Iaddend.into said .[.opening.]. .Iadd.openings.Iaddend.. 19. A fuel arrangement for a nuclear reactor comprising .[.at least one.]. .Iadd.a plurality of .Iaddend.elongated fuel .[.element.]. .Iadd.elements disposed in a generally parallel array, means for positioning said fuel elements, said array including fuel elements that are permitted to individually expand and contract longtiduinally relative to said positioning means, said means positioning laterally in spaced relationship all of said fuel elements that are permitted to individually expand and contract longitudinally and slip relative to said positioning means, said positioning means engaging each of said expanding fuel elements and .Iaddend..Badd.formed by a plurality of rigid walls .Baddend..Iadd.including substantially .Iaddend.rigid means .Badd.on said walls .Baddend.engaging one side of .Iadd.each of .Iaddend.said .Iadd.expanding .Iaddend.fuel .[.element.]. .Iadd.elements .Iaddend.to laterally position said .Iadd.expanding .Iaddend.fuel .[.element.]. .Iadd.element.Iaddend., resilient means .Badd.integrally formed on and from said walls .Baddend.disposed on a side of .Iadd.each of .Iaddend.said .Iadd.expanding .Iaddend.fuel .[.element.]. .Iadd.elements .Iaddend.generally opposite to said one side and engaging said .Iadd.expanding .Iaddend.fuel .[.element.]. .Iadd.elements respectively .Iaddend.to bias the latter into engagement with said rigid means, one of .Iadd.each of .Iaddend.said resilient means and said rigid means being longitudinally spaced along said fuel .[.element.]. .Iadd.elements respectively .Iaddend.to form a pair of spaced members, and the other of .Iadd.each of .Iaddend.said resilient means and said rigid means being positioned intermediate said pair of members. .Iadd. 20. The fuel arrangement of claim 19 including means for fixedly positioning each of said rigid and resilient means longitudinally with respect to each of said expanding fuel elements. .Iaddend..Iadd. 21. The fuel arrangement of claim 20 including means for fixedly positioning said rigid means laterally with respect to each of said expanding fuel elements. .Iaddend. .Iadd..[..[.22. A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, a plurality of longitudinally spaced grid members extending laterally across said fuel arrangement for positioning laterally in spaced relationship all of said fuel elements in said array that are permitted to individually expand longitudinally and slip relative to said grid members, said expanding fuel elements each of said grid members comprising a plurality of connecting members forming a plurality of fuel element openings, each of said expanding fuel elements extending through an opening in each grid member, and forming a segment of a flow channel between said fuel elements, substantially rigid means rigidly engaging one side of each of said expanding fuel elements respectively to laterally position each expanding fuel element yet permit longitudinal slippage thereof, resilient means disposed on another side of each expanding fuel element generally opposite to said one side and engaging respectively each expanding fuel element to bias the latter into engagement with said rigid means, one of said rigid means and said resilient means extending from said connecting members into said opening, and the other of said rigid means and said resilient means being located in said flow channel..]..]..Iaddend..Iadd. 23. The fuel arrangement of claim 14 including rigid spacer means extending longitudinally between said grid members and fixedly secured thereto to space said grid members longitudinally with respect to said expanding fuel elements. .Iaddend. .Iadd..[..[.24. The fuel arrangement of claim 22 including rigid spacer means extending longitudinally between said grid members and fixedly secured thereto to space said grid members longitudinally with respect to said expanding fuel elements..]..]..Iaddend..Iadd. 25. The fuel arrangement of claim 14 wherein said resilient means is preloaded with a force sufficient to overcome those displacement forces respectively acting on said expanding fuel elements and tending to move said fuel elements laterally away from said rigid means. .Iaddend..Iadd. 26. .[..[.The fuel arrangement of 14 wherein are.]..]..Iaddend. .Badd.A fuel arrangement for a nuclear reactor comprising a plurality of elongated fuel elements disposed in a generally parallel array, a plurality of longitudinally spaced grid members extending laterally across said fuel arrangement, said array including fuel elements that are permitted to individually expand and contract longitudinally relative to said grid members, said grid members positioning laterally in spaced relationship all of said fuel elements in said array that are permitted to individually expand and contract longitudinally relative to said grid members, each of said grid members having respective openings therein, all of said longitudinally expandable fuel elements in said array extending through respective openings in each grid member, each of said grid members having both resilient means and substantially rigid means extending into each of said last mentioned openings for supporting all of said longitudinally expandable fuel elements against lateral displacement, and said resilient means being disposed generally opposite to said rigid means, and .Baddend..Iadd.said resilient means formed integrally upon .Iaddend..Badd.and from .Baddend..Iadd.said grid members.Iaddend.. .Iadd. 27. The fuel arrangement of claim 14 wherein each of said grid members is formed by a plurality of cross-laced interconnected rigid straps. .Iaddend..Iadd. 28. The fuel arrangement of claim 14 wherein said some fuel elements comprise at least a majority of said fuel elements in said fuel arrangement..Iaddend..Iadd. 29. A fuel arrangement for a nuclear reactor comprising a plurality of fuel elements disposed in a generally parallel array, means for supporting said fuel elements for limited longitudinal movement to permit expansion and contraction of each movable fuel element relative to said supporting means and independently of expansion and contraction of the other longitudinally movable fuel elements, a plurality of grid members spaced apart longitudinally of said array and each extending laterally across said array for positioning laterally in spaced relationship all of said longitudinally movable fuel elements, rigid spacer means extending longitudinally of said array between said grid members and rigidly secured to all of said grid members to space said grid members longitudinally with respect to the fuel elements, each of said grid members comprising peripheral straps and two sets of intersecting and rigidly interconnected inner straps with said inner straps of one set extending transversely of said inner straps of the other set, said inner and peripheral straps cooperating to form a plurality of openings, respective openings in said grids being aligned longitudinally of said array to form groups of aligned fuel element openings respectively accommodating the longitudinally movable fuel elements passing therethrough, there being a group of longitudinally aligned fuel element openings for each longitudinally movable fuel element, each said inner strap including a plurality of pairs of rigid means formed integrally thereon, the rigid means of each pair being spaced from each other longitudinally of the array and the different pairs being spaced apart along each strap in a direction transversely of the array, each pair of said rigid means engaging one side of one of said longitudinally movable fuel elements to laterally position each such fuel element yet permit longitudinal slippage thereof, a plurality of spaced apart resilient springs formed integrally with each inner strap, each such resilient spring being formed longitudinally intermediate one pair of said rigid means and extending outwardly from said inner strap in a direction away from the latter pair of rigid means, the resilient springs being spaced along each inner strap in a direction transversely of the array and by a distance approximating the spacing between the pairs of rigid means formed along that inner strap, said resilient springs engaging another side of said longitudinally movable fuel elements generally opposite to said one side to bias each of said longitudinally movable fuel elements into engagement with one pair of said rigid means, there being at least one pair of rigid means and one spring extending into each fuel element opening for the longitudinally movable fuel elements. .Iaddend..Iadd. 30. The fuel arrangement of claim 29 wherein said resilient springs are preloaded with a force sufficient to overcome those displacement forces respectively acting on said longitudinally movable fuel elements and tending to move said fuel elements laterally away from said rigid means. .Iaddend.