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Ab Asea-atom

Anders Wallander

Bo Borrman

Anders Soderlund

Tommy Gustafsson

Magnus Gronlund

Patrik Andersson

Arne Mansson

The present invention relates to a fuel assembly (,) and a method therefor. The fuel assembly is intended for a light-water cooled nuclear reactor and comprises a first and a second locking member (,), a plurality of elongated elements (,) wherein each of the lower ends of the elongated elements is provided with an end plug (,). The end plug (,) is arranged guided or locked in an end plate (,) which comprises at least two adjacently disposed plug holes (,) for receiving one end plug (,) each. The first locking member (,) is made in an end plug (,) and has a concave shape and the second locking member (,) is arranged slidable in a locking hole (,) which is adapted to extend between the two adjacently disposed plug holes (,) and opening out into these. The second locking member (,) is made with a length exceeding the length of the locking hole (,) and has end surfaces with shapes intended for cooperation with the concave surface of the first locking member (,).

Device and method for locking rods in a bottom tie plate of a fuel assembly

A fuel assembly (16) for a boiling-water nuclear reactor arranged in groups with four fuel assemblies in each group and with a centrally placed control rod (17) forming a supercell. Each fuel assembly (16) includes a plurality of vertical fuel rods (12) with enriched nuclear fuel material (24), said rods being arranged between a bottom tie plate (13) and a top tie plate (14) in a surrounding vertical fuel channel (1) which is connected to a transition section (2). The transition section is provided with holes (20a-d) for by-pass flow outside the fuel assembly. The fuel assembly is characterized in that the by-pass holes are arranged in such a way that when turning the fuel assembly (16), including the transition section (2), 90.degree., 180.degree. or 270.degree. around the longitudinal axis of the fuel assembly, said holes are adapted to direct the by-pass flow away from the control rod (17).

Fuel assembly for a boiling water reactor

To allow manipulation of the fuel assemblies in a nuclear reactor, the assemblies are provided with a lifting handle at the upper end. A top support is provided at the lifting end of the fuel assembly to determine the spacing. An upper end portion of the fuel channel for the fuel assemblies surrounds a lifting plate or the like for the fuel rods, where the lifting plate and handle together may form a lifting member cast in one piece. To simplify manipulation of the fuel assemblies during fuel inspection, for instance, and reduce the risk of losing small parts, a top support lock (1) for the top support (2) has been constructed in the handle (3). When assembling the top support (2), the top support lock (1) is moved to its open position and the angle-piece ends (5) are inserted through recesses (8) in the fuel channel (7) up to the openings (4) in the handle (3). When the angle-piece ends (5) of the top support are in place, the holes (6) in the angle-piece ends will be immediately opposite the holes (4) in the handle (3) and the top support lock (1) is moved to its closing position by a spring (13). With a good fit between the top support and the openings in the fuel channel and in the handle, the top support will be accurately positioned and firmly secured. When the top support is to be dismantled, the top support lock (1) is moved to its open position and the top support (2) is removed from openings (4, 8) in the handle and fuel channel.

Top support lock

A fuel assembly for a boiling water reactor comprises four bundles of vertical fuel rods (5). The bundles are surrounded by a common fuel channel (2) and each provided with a top tie plate (10) and a bottom tie plate (11). The four bottom tie plates are supported by a common supporting plate (18) which is inserted into, and supported by, the inlet sleeve (15) of the fuel assembly. Each bottom tie plate (11) includes an annular horizontal contact surface (24) abutting the supporting plate, and a non-round guide portion which is arranged, with no mentionable play, in a corresponding, non-round, through-hole (19) in the supporting plate (18).

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Vasteras, Sweden

Anders Wallander