Reversible BWR fuel assembly and method of using same
AssigneeWestinghouse Electric Corp.
InventorsThomas R. Freeman, John F. Wilson, Ronald P. Knott
Life of this patent
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Abstract
A fuel assembly, particularly advantageous for use with a BWR, wherein the fuel bundle is adapted to be inserted into an envelope formed from a flow channel and a lower nozzle assembly. The fuel bundle is essentially axially symmetrical having identical top and bottom tie plates. Within the fuel bundle, alternate fission gas plenums are disposed at the top and bottom of the bundle respectively. During the refueling operation, the fuel bundle is removed from the reactor core, axially inverted and reinserted into the core for continued burn up. The invention takes advantage of the reactivity increase possible in a BWR when a partially burned fuel bundle is inverted.
Claims15
A nuclear fuel assembly comprising:
- (a) a flow channel;
- (b) a lower nozzle assembly structurally attached to said flow channel to form therewith an external envelope;
- (c) an invertible fuel bundle adapted to be inserted into said envelope, said fuel bundle comprising a plurality of elongated fuel rods held in a spaced lateral array between top and bottom tie plates, each of said top and bottom tie plates being substantially identical and having means for supporting said fuel bundle within said envelope in either of two mututally inverted vertical orientations whereby the orientation of the fuel bundle in a flow channel may be reversed during burn-up operation.
A method of operating a nuclear reactor having a core containing a fuel bundle external envelope comprising a flow channel and a bottom nozzle assembly, said method comprising the steps of:
- (a) inserting a nuclear fuel bundle having substantially identical top and bottom tie plates into said external envelope with one of said top and bottom tie plates engaging said bottom nozzle assembly to support said fuel bundle thereon;
- (b) operating said reactor for a period of time;
- (c) withdrawing said fuel bundle from said envelope;
- (d) inverting said fuel bundle;
- (e) reinserting said inverted fuel bundle into said envelope with the other of said top and bottom tie plates engaging said bottom nozzle to support said fuel assembly thereon;
- and
- (f) continuing to operate said reactor with said inverted fuel bundle.
A method of operating a BWR nuclear reactor having a core containing a fuel bundle envelope comprising a flow channel and bottom nozzle assembly, said method being operable to enhance burn up of nuclear fuel and to reduce fuel cycle operating costs and comprising the steps of:
- (a) inserting the self-supporting nuclear fuel bundle having substantially identical top and bottom tie plates into said fuel bundle envelope with one of said top and bottom tie plates engaging said bottom nozzle assembly to support said fuel bundle thereron;
- (b) operating said reactor for a period of time to partially burn said fuel whereby fuel positioned at the lower portion of said fuel bundle is burned to a larger extent than fuel positioned at an upper portion of said fuel bundle;
- (c) withdrawing said fuel bundle from said envelope;
- (d) inverting the top and bottom of said fuel bundle;
- (e) reinserting said inverted fuel bundle into said envelope whereby the fuel burned to a larger extent is positioned at the upper portion of the fuel bundle;
- (f) continuing to operate said reactor with said inverted fuel bundle whereby the fuel in said fuel bundle is more evenly burned.
Dependencies are inferred from the claim text.